The present invention relates to motor-driven or riding vacuum machines of the type used to clean litter, debris and dirt or sand from public parkways, streets, sidewalks, and large open areas such as parking lots, parks, and the like. Vehicles of this type are designed to recover a large range of litter, including dust, dirt, sand and debris, bottles, cans, clippings, hedge trimmings, and the like.
The present invention relates to improvements in litter vacuums. A first improvement is directed to the suspension of the vacuum housing or xe2x80x9cshoexe2x80x9d and the mounting of the forward or xe2x80x9ccornerxe2x80x9d sweeper brushes. An actuator such as an hydraulic cylinder operated by the operator rotates a crank which lifts the vacuum shoe. A four-bar or parallelogram linkage suspends the vacuum shoe to the chassis or frame of the vehicle so that it may be moved between a lowered use position and a raised transport position. Moreover, the forward portion of the vacuum housing is mounted by means of linkages having slots or xe2x80x9clost motionxe2x80x9d links so that when the vacuum housing is in the lowered or use position and the housing rests on rollers or wheels to provide the proper operating height, the vacuum housing may ride over obstacles or bumps independently of the corner sweeper brushes. At the same time, if the operator sees an unusually large object in the way, such as a quart or liter plastic bottle, he may actuate a cable to raise the vacuum shoe to permit it to accommodate the large object, and suction the object up. Again, this raising of the vacuum shoe is independent of the sweeper brushes.
The sweeper brushes are mounted to the same hydraulic lift mechanism which raises and lowers the vacuum shoe. However, the brushes may be latched in the raised or storage position to permit the vacuum shoe to be used on gross or outdoor carpeting. The sweeper brushes are mounted on linkages which permit an articulated motion of the brushes. Each brush is mounted similarly to the other so that only one need be described. The brushes operate independently of each other. If a corner brush encounters an object head-on in the sweeping position, it is permitted, against a spring bias, to rotate outwardly and rearwardly, about a vertical pivot located inwardly and rearwardly of the vertical center of the brush. This permits the brush to move rearwardly of the forward-moving machine without damage. It also increases the moment arm by which a second articulated arm on which the brush is mounted may move inwardly toward the center of the machine, folding the brush beneath the chassis or frame in cooperation with the first articulating link and protecting the brush against further damage.
Thus, the shoe and brushes may be raised for transport or storage or lowered for use while the brushes may be latched in the storage position as the vacuum shoe is used for suctioning debris, and the shoe may be independently raised for larger objects.
The vacuum shoe is equipped with a door mounted to close or adjust the inlet opening by a cable controlled by the operator. The door is provided with a flexible lower strip to adjust to the surface being cleaned. By closing the inlet opening, the operator may control the velocity of the air entering the front of the vacuum shoe and directing the incoming air to pass close to the surface being cleaned. This section entrains dust, debris and smaller particles such as sand into the suction air stream from which the debris is filtered and collected.
Another improvement incorporates a scrim bag to collect and filter the debris in a hopper which may be pivoted to dump the contents. This improvement renders unnecessary a supplemental refuse container. The scrim bag is disposable and coupled to an inlet from the blower to receive the debris. Air passing through the scrim bag and not passing through the main filter is recirculated to the vacuum shoe. A disposing plastic bag is mounted in a flat configuration adjacent a rear hopper door. When it is desired to dispose of the material collected in the scrim bag, the hopper door is unlatched, the hopper is rotated to the dump position, and the scrim bag and its contents falls into the plastic trash bag which is then secured so the contents may be disposed of.
As an alternative, when the debris is primarily larger material such as lawn clippings or trimmings or cups and plates, a scrim bag may be used to collect debris and the scrim bag may be emptied directly into a refuse container.
The present invention also includes provisions for a recirculation aperture in the hopper at a location between the solid walls of the hopper and the scrim bag or other filter bag in the hopper. Refuse entrained in the suction air is introduced through the hopper into a pre-filter bag. Air (and some smaller particles) passes through the filter bag and exits the hopper, through a final filter which extracts xe2x80x9cfinesxe2x80x9d or dust from the air before exhausting the air into the atmosphere. The debris, once it enters the filter bag, tends to settle down because the velocity of the suction air decreases in the larger volume of the hopper. By placing the inlet of a recirculation conduit between the wall of the hopper yet outside the filter bag, the recirculating aperture acts as a differential pressure regulator responsive to the pressure across the final filter. If the final filter becomes clogged, the pressure across it increases, and a greater amount of air is then recirculated to the vacuum housing. This extends the useful time of the final filter before replacement or cleaning the final filter.
Other features and advantages of the present invention will be apparent to persons skilled in the art from the following description of the illustrated embodiment accompanied by the attached drawing whether identical reference numerals will refer to like parts in the various views.